Australian Antarctic Division: Leading Australia’s Antarctic Program

Measuring Sea Ice

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This week at Mawson: 23 August 2013

Sea ice measurements

Since the beginning of April we have seen the sea turn to ice. As part of a scientific program the thickness of the ice is measured each week when the ice is thick enough to travel on safely. Four spots are drilled each year at Mawson and these include West Bay, East Bay, Kista Straight and Horseshoe Harbour. The exact positions are found by using a GPS and then a cane pole was placed in the hole as a marker.

This week I got to go out with our Field Training Officer (FTO) to take the measurements. There are three measurements we record which are the thickness of the ice, the thickness of the snow on top of the ice and the distance from the top of the ice to the water which comes up the drilled hole. When first drilled the ice was approximately 400mm thick and when we did it last the average thickness was 1300mm. West Bay was the thickest at 1390mm and Kista Straight was 1210mm. Some results from the last couple of months are in the table below.

DATE

EAST BAY

WEST BAY

HORSESHOE HARBOUR

KISTA STRAIGHT

04/06/13

ICE

900

900

1000

800

SNOW

80

10

100

100

WATER

40

80

60

30

14/06/13

ICE

1000

1000

1020

1000

SNOW

100

90

100

100

WATER

50

80

45

50

24/06/13

ICE

1100

1100

1150

1000

SNOW

80

0

110

60

WATER

80

100

60

60

08/07/13

ICE

1080

1150

1220

1000

SNOW

40

25

80

70

WATER

80

110

70

60

17/07/13

ICE

1100

1200

1200

1020

SNOW

50

20

80

50

WATER

100

110

100

70

27/07/13

ICE

1200

1250

1280

1100

SNOW

40

10

80

80

WATER

110

130

80

80

01/08/13

ICE

1250

1320

1300

1180

SNOW

60

10

70

70

WATER

90

110

90

70

12/08/13

ICE

1300

1390

1380

1210

SNOW

30

10

60

60

WATER

130

130

90

80

This time of year when the ice is approaching its thickest going on previous records. Kista Straight is normally below the other as there is a strong current running through the water. Also if there is a large amount of snow on the ice it acts like an insulator and stops the ice from growing thicker. I find it very interesting how nature works and also don’t mind the advantage to get off station for an hour or so.

With a smile, Trent

The drill in the back of the Hagg(Photo: Trent Juillerat)

Marker in the Kista Straight(Photo: Trent Juillerat)

Trent drilling in Kista Straight(Photo: John Burgess)

Trent drilling in East Bay with berg in Background(Photo: John Burgess)